The present invention relates to a tarpaulin with thermal insulation for a swimming pool, consisting of a closed-clelularly foamed, elastic plastic foil with flotation features.
Tarpaulins of this type are used on swimming pools in order to prevent heat loss of the water and at the same time to prevent pollution of the latter due to algae growth and flying dust. Such tarpaulins have been used widely especially on private swimming pools which are not used routinely and which are frequently equipped only with makeshift water treatment facilities.
German Utility Pat. No. 7,527,184 shows a tarpaulin of this type which consists of a cross-linked polyolefin foil foamed with closed cells, and on the top side of which a fiber-reinforced cover foil is affixed. Initially, the tarpaulins have proved excellent, however, after extended use it has proved in the meantime that their great function value is yet open to improvement.
Older swimming pools frequently do not have a rolling-up device for the swimming pool tarpaulin, and in these cases the cover must be pulled off the water surface by hand; a process which for instance children should be able to perform. A constant, low weight is therefore of great importance, and in the case of the known tarpaulin considerable difficulties arose especially in regard to this point. Apparently due to diffusion processes, water concentration within the closed cells of the foam material developed so that their weight per unit area could increase by ten to fifteen times in extreme cases. A decrease of thermal insulation developed parallel to this weight increase.
It is considered an additional disadvantage that the soft-elastic construction of the underneath of the tarpaulin was a considerable hindrance particularly when pulling it over sharp edges of the pool; moreover, the underneath of the tarpaulin could be damaged.